For most of human history, we had a lot of bad ideas about how we were getting sick. We also had plenty of bad ideas about how to prevent it, like bloodletting, drilling large holes in the head and drinking arsenic.

We really only started to figure out how to effectively fight infectious disease about 200 years ago, when, inspired by milkmaids, a doctor named Edward Jenner decided to take a closer look at a promising folk remedy - the surprising details we'll leave for the video.

Humans get along pretty well with most microbes. Which is lucky, because there are a lot more of them in the world than there are of us. We couldn't even live without many of them. But a few hundred have evolved, and are still evolving, to exploit our bodies in ways that can make us really sick. These are the microbes we call germs. Think plague, flu, HIV, SARS, Ebola, Zika, measles.

This is a series is about where germs come from. In this first of three episodes, we see what our early encounters with germs may have been like — and how germs first got the upper hand.

Why do we humans like to play so much? Play sports, play tag, play the stock market, play duck, duck, goose? We love it all. And we're not the only ones. Dogs, cats, bears, even birds seem to like to play. What are we all doing? Is there a point to it all?

They're from the same ethnic group. They speak the same language. And they live on both sides of the Liberia-Guinea divide in the area around Liberia's eastern border city of Ganta, in Nimba County. The families straddle the border, which is not fenced.

"Right over there is the border," says businessman Prince Haward, directing our attention to some rubber farms not too far away. "Those are the rubber farms you find in Guinea."

Monrovia, Liberia's capital, is a city that relies on public transportation — buses, private vans (also known locally as buses), cars and motorcycle taxis. And you can't use any of these options without coming into contact with other people, whether you're jostling in line or wrapping your arms around a motorcycle taxi driver.

Since the Ebola outbreak, Monrovia has placed new restrictions on public transport, and fewer drivers are willing to take chances. So there aren't as many options for commuters at a time when Ebola has made everyone afraid of touching strangers.

Ebola has been responsible for many hundreds of deaths, for fear, for panic, for disbelief and anger.

And for a catchy dance song: "Ebola in Town."

The producers behind this unlikely music are Samuel "Shadow" Morgan and Edwin "D-12" Tweh, who grew up in the shadow of war. They both spent time as kids in refugee camps in Ghana after fleeing the civil war back home in Liberia.

So let's cut to the chase. Depending on where you live on Earth, cooking dinner, having sex and going to the bathroom are either three of life's many pleasures, or they're the riskiest things you can do.

Former Clinton and Obama speechwriter Jon Lovett knocked it out of the park last year at Pitzer College's commencement. We asked the brilliant animator Steve Cutts to bring part of his address to life in pictures. You will likely never look at a commencement gown the same way again.

Reporter Liz Halloran and I have been motoring around New Hampshire the past few days, chasing candidate events and taking the political temperature of the state.

On the way to a Santorum event Thursday we spotted a small lake dotted with ice fishing shelters — the first we'd seen all week. Apparently, the ice only became thick enough in the last two weeks or so.